|By Suzannah Gonzales

(Reuters) - Former USA Gymnastics doctor Larry Nassar has been transferred to a high security federal prison in Tucson, Arizona, after being convicted of molesting scores of young women who went to him for treatment, authorities said on Saturday.

The Federal Bureau of Prisons said the 54-year-old Nassar was at the United States Penitentiary, Tucson, which holds about 1,390 male inmates. The bureau's website listed his release date as March 23, 2069.

After weeks of horrifying testimony from nearly 200 victims about his decades of abuse, Nassar was sentenced on Monday in Michigan to 40 to 125 years in prison.

He had already received a 40-to-175-year sentence in a neighboring Michigan county, and was sentenced to a 60-year federal term for child pornography convictions.

Prosecutors have said there are about 265 known victims in total, including Olympic gold medalists McKayla Maroney and Aly Raisman.

The Nassar scandal has prompted multiple investigations into why the U.S. Olympic Committee, the sport's governing body USA Gymnastics, as well as Michigan State University, where Nassar also worked, failed to investigate complaints about him going back years.

United States Olympic Committee Board of Directors Chairman Larry Probst said on Friday before the opening ceremony of the Pyeongchang Winter Games in South Korea that the U.S. Olympic system "failed" the hundreds of young female athletes who were sexually abused by Nassar.

The U.S. Olympic Committee has launched an investigation into its own conduct as well as that of USA Gymnastics and U.S. lawmakers are also investigating.

Senior officials at USA Gymnastics and Michigan State have been forced to resign in recent weeks.

(Reporting by Suzannah Gonzales in Chicago; Editing by David Gregorio)